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Tytuł:
Electrical Properties of Lead Phthalocyanine Films
Autorzy:
Abd El-Rehim, N.
El-Samahy, A.
Powiązania:
https://bibliotekanauki.pl/articles/1946191.pdf
Data publikacji:
1996-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.-i
Opis:
Current density-voltage characteristics have been obtained from thin films of lead phthalocyanine particles dispersed in a polymer binder when sandwiched between ohmic gold and blocking aluminium electrodes. At low voltages, the current in the forward direction shows Schottky diode behaviour. The diode parameters are evaluated using the model of Cheung and Cheung. Barrier heights and widths are determined as a function of applied voltage. A number of parameters is evaluated on the basis of the theory of space-charge-limited conduction, and the following values are obtained: p$\text{}_{0}$ = 8.5 × 10$\text{}^{18}$ m$\text{}^{-3}$, concentration of the traps per unit energy range at the valence band P$\text{}_{0}$ ≈ 2.5 × 10$\text{}^{44}$ J$\text{}^{-1}$m$\text{}^{-3}$, temperature parameter of trapping distribution T$\text{}_{c}$ ≈ 500 K and total trapping concentration, N$\text{}_{t}$ ≈ 1.7 × 10$\text{}^{24}$ m$\text{}^{-3}$.
Źródło:
Acta Physica Polonica A; 1996, 90, 3; 557-564
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
AC Electrical Conductivity and Dielectric Properties of Perovskite $(Pb,Ca)TiO_3$ Ceramic
Autorzy:
El-Mallah, H.
Powiązania:
https://bibliotekanauki.pl/articles/1419850.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.45.Gm
72.20.-i
72.80.-r
Opis:
$Pb_{1 - x }Ca_{x}TiO_3$ perovskite crystalline structure with x = 0, 0.2, 0.6, 0.7, and 0.8 were prepared by mixture method. The ac conductivity and dielectric properties of the studied bulk compositions have been investigated in the frequency range $1 \times 10^3 - 5 \times 10^6 Hz$ and temperature range 303-473 K. The experimental results indicate that the ac conductivity $\sigma_{ac}(\omega),$ dielectric constant ε' and dielectric loss ε" depend on the temperature and frequency. The ac conductivity was found to obey the power law $\omega^{S}$ with the frequency exponent S > 1 decreasing with increasing temperature. The present results are compared to the principal theories that describe the universal dielectric response behavior. Values of dielectric constant ε' and dielectric loss ε" were found to be temperature and frequency dependent and the maximum barrier height $W_{m}$ is calculated.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 174-179
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytic Approximations for Thomas-Fermi Equation
Autorzy:
El-Nahhas, A.
Powiązania:
https://bibliotekanauki.pl/articles/1812056.pdf
Data publikacji:
2008-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Hq
02.30.Mv
02.60.Lj
21.10.Ft
31.15.-p
Opis:
In this paper, we give an analytic approximation to the solution of the Thomas-Fermi equation using the homotopy analysis method and with the use of a polynomial exponential basis.
Źródło:
Acta Physica Polonica A; 2008, 114, 4; 913-918
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground-State Structure of a Two-Electron Quantum Dot
Autorzy:
El-Said, M.
Powiązania:
https://bibliotekanauki.pl/articles/2014017.pdf
Data publikacji:
2000-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
Opis:
The energy spectrum of two interacting electrons, confined in a parabolic quantum dot, presented in a magnetic field is obtained. We have analyzed the energy level crossings between spin-singlet and spin-triplet states. The influence of the quantum dot size on these crossings is also shown. The results of our calculations seem to be in good agreement with analytical and exact numerical data.
Źródło:
Acta Physica Polonica A; 2000, 97, 6; 1023-1032
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Elastic Model for Lagrangian Turbulence and Diffusion
Autorzy:
El Naschie, M.
Powiązania:
https://bibliotekanauki.pl/articles/1887647.pdf
Data publikacji:
1991-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.40.Gc
Opis:
Using a special analogy to a parametrically forced mathematical pendulum with energy flux, it is attempted here to model the vortex wake in a fluid due to the movement of a cylindrical solid body. We also show that the path taken by certain fluid particles represents a homoclinic soliton and corresponds to a spacial separatrix. This in turn may lead through deterministic fluctuation to diffusion-like chaotic motion.
Źródło:
Acta Physica Polonica A; 1991, 79, 6; 757-764
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Free-Electron Analysis of Optical Properties of Thermally Evaporated Gold Films
Autorzy:
El-Kadry, N.
Powiązania:
https://bibliotekanauki.pl/articles/1931626.pdf
Data publikacji:
1994-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Er
78.66.Bz
Opis:
Gold films of thicknesses 150-300 Å were deposited on quartz substrata using vacuum evaporation technique. Spectrophotometric measurements of transmission T and reflection R at normal incidence were performed in the range 0.4-3.0 µm. The real and imaginary parts of the complex refractive index ñ were determined using a developer algorithm bashed on Murmann's exact equations. The accuracy in the determined n and k was found to be ±6.0% and ±1.6%, respectively. The dispersion curve of n slowed an anomalous dispersion in the visible region characterized by a peak at λ = 0.840 µm. The dielectric constants were calculated and presented. The Drude model parameters ω$\text{}_{p}$ and ω$\text{}_{τ}$ and d.c. conductivity were determined and compared. The results showed that such parameters could be obtained from free-electron analysis for the near IR experimental results and the intraband transition contributes significantly to the dielectric functions.
Źródło:
Acta Physica Polonica A; 1994, 86, 3; 375-383
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Peano Dynamics as a Model for Turbulence and Strange Nonchaotic Behaviour
Autorzy:
El Naschie, M.
Powiązania:
https://bibliotekanauki.pl/articles/1887906.pdf
Data publikacji:
1991-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.45.+b
Opis:
The note outlines a scenario for a two-dimensional dynamic system to possess strange nonchaotic behaviour in the presence of two frequency quasi periodic forcing. Implications for turbulence are also discussed.
Źródło:
Acta Physica Polonica A; 1991, 80, 1; 3-13
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlation Length in PBnA Liquid Crystal Family
Autorzy:
El Guermai, K.
Ayadi, M.
El Boussiri, K.
Powiązania:
https://bibliotekanauki.pl/articles/1992845.pdf
Data publikacji:
1998-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.-v
61.10.-i
64.70.Md
61.30.Gd
Opis:
We present a study of the range molecular interactions inside layers in smectic phases A and I of PBnA (phenyl-4 benzylidene 4'-alkylaniline) liquid crystals family. The purpose of this work is to determine the correlation length of the molecules' gravity centers in existing domain of smectic phases and at the transition between them. We used X-rays in-plane peaks of the pattern diffraction of aligned sample by a magnetic field.
Źródło:
Acta Physica Polonica A; 1998, 94, 5-6; 779-784
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
DSC Studies of Some Bismuth-phosphate Glasses
Autorzy:
El-Adawy, A. A.
Powiązania:
https://bibliotekanauki.pl/articles/1992707.pdf
Data publikacji:
1998-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.+g
Opis:
The differential scanning calorimetry measurements were made on a series of bismuth-iron-phosphate glasses over a temperature range around the glass transition temperature. The activation energy for structural relaxation, ΔH, was determined and found to increase with the metal-to-phosphorus ratio. The differential scanning calorimetry data were analyzed using the Adam-Gibbs-Scherer model of the glass transition. This analysis suggests that these glasses undergo a transition from the strong to the fragile glass regime as the metal-to-phosphorus ratio is increased.
Źródło:
Acta Physica Polonica A; 1998, 94, 4; 661-670
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effects of Relativistic Warm Plasma Waveguide and High Frequency Electrical Field on Beam-Plasma Interaction
Autorzy:
El-Shorbagy, Kh. H.
Powiązania:
https://bibliotekanauki.pl/articles/2047358.pdf
Data publikacji:
2007-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.27.Ny
52.35.-g
94.20.wf
Opis:
The paper is concerned with investigation of the influence of an intense high frequency electric field and relativistic warm plasma waveguide on electrostatic oscillations of nonuniform bounded plasma. The stabilizing effect of a strong high frequency (pump) electrical field on beam-plasma interaction in a cylindrical relativistic warm plasma waveguide is discussed. A new mathematical technique "separation method" was applied to the two-fluid plasma model to separate the equations, which describe the system, into two parts, time and space parts. Plasma electrons are considered to have a relativistic, thermal velocity. It is shown that a high frequency electric field has no essential influence on dispersion characteristics of unstable surface waves excited in a relativistic warm plasma waveguide by a low-density electron beam. The region of instability is only slightly narrowing and the growth rate decreases by a small parameter and this result was reduced comparing to cold, nonrelativistic plasma. Also, it is found that the plasma electrons did not affect the solution of the space part of the problem.
Źródło:
Acta Physica Polonica A; 2007, 112, 1; 41-48
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Heat Treatment on the ac Conductivity and Dielectric Properties of Ag$\text{}_{33}$Sb$\text{}_{31}$Se$\text{}_{36}$ Thin Films
Autorzy:
Abd El-Wahabb, E.
Powiązania:
https://bibliotekanauki.pl/articles/2044570.pdf
Data publikacji:
2005-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.-r
77.55.+f
81.40.Rs
81.40.Tv
81.40.Ef
Opis:
The effect of heat treatment on the ac conductivity and dielectric properties of the melt quenched and thermally evaporated Ag$\text{}_{33}$Sb$\text{}_{31}$Se$\text{}_{36}$ chalcogenide system are reported for the first time. The results of the alternating current conductivity σ$\text{}_{ac}$, the dielectric constantε$\text{}_{1}$, and the dielectric lossε$\text{}_{2}$ of the Ag$\text{}_{33}$Sb$\text{}_{31}$Se$\text{}_{36}$ thin film samples are presented over the temperature range 303-373 K and the frequency range 0.1-100 kHz. The temperature dependence of the ac conductivity σ$\text{}_{ac}$(ω) and the frequency exponent s are discussed with the aim of the correlated barrier hopping model. Values of σ$\text{}_{ac}$(ω),ε$\text{}_{1}$, and ε$\text{}_{2}$ were found to increase with the increase in the annealing temperature due to the reduction of the number of unsaturated defects which decrease the density of localized states in the band structure.
Źródło:
Acta Physica Polonica A; 2005, 108, 6; 985-996
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of Capillary Motion of Water in Bricks Using Neutron Radiography
Autorzy:
Czachor, A.
El-Ghany El-Abd, Abd
Milczarek, J. J.
Powiązania:
https://bibliotekanauki.pl/articles/2035490.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Rm
28.20.-v
47.55.Mh
Opis:
Vertical migration of water in several porous materials has been directly observed and recorded with the recently installed neutron and gamma radiography facility at the MARIA reactor of Institute of Atomic Energy, Świerk. The density profiles of water in samples were obtained from the optical density of digitised images. A simple model (representing the porous material as the collection of capillary tubes of various radii) has been introduced to describe the liquid transport in porous materials in terms of capillary motion. The equation for viscous movement of water in porous material in presence of the gravitation is proposed. A good agreement of the calculated density profiles for vertical water migration with the data collected for siliceous bricks suggests that the thinnest capillary tubes determine the upper edge of the water density profile.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 245-252
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of Painting Layers of Sennefer Tomb by Ion Beam Analysis
Autorzy:
Abd El Aal, S.
Powiązania:
https://bibliotekanauki.pl/articles/1504061.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.En
07.60.Pb
Opis:
Egypt has many pharaonic tombs for kings, queens and noblemen. The Sennefer tomb, one of the most important nobleman tombs, is located in the southern hillside of Sheikh Abd El-Qurna - west side of Luxor. It is dated back to 1439-1413 B.C. (18th Dynasty) and is usually referred as the Tomb of Vines, due to the large part of the ceiling of the burial chamber. The vine tomb was carved inside a mountain, its walls are covered with plaster and were painted using the tempera technique (pigments mixed with organic binding medium). The analysis was performed by using particle-induced X-ray emission, microbeam particle-induced X-ray emission and optical microscope for the six samples from the Vine tomb such as white, black, red, yellow, blue and green pigments and for the ground layers of the tomb in order to identify the composition of plaster layers and pigments. The data about the nature of these materials are indispensable for conservation and cleaning.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 144-148
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemical characters of the Gabbroic Rocks in ophiolite sequences of north Hatta area, United Arab Emirates
Autorzy:
El Tokhi, M.
El Din Mahmoud Amin, B.
Arman, H.
Powiązania:
https://bibliotekanauki.pl/articles/1070383.pdf
Data publikacji:
2016-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
91.62.Rt
92.20.Ny
Opis:
The ophiolite sequences of UAE, as a part of Oman ophiolite, represent both, mantle section and crustal section. The crustal part of the ophiolite sequences, consists of a layered series (cumulate peridotites and gabbros). This paper aims to overview geochemical character and some mechanical and physical features of the gabbroic rocks. The gabbros comprise troctolite, olivine gabbro, normal gabbro, gabbronorite, and uralitized gabbros. Geochemical features indicate that they are tholeiitic and are formed in an arc-related tectonic setting. On NMORB normalized pattern of gabbros, the HFS-elements (P, Zr, Sm, Ti, and Y) show a flat pattern parallel to NMORB. In contrast, the LIL-elements (Rb, Ba, Th, Sr) are relatively more enriched than NMORB. The enrichment of LIL-elements over the HFS-elements and the depletion of Nb relative to other HFS-elements suggest involvement of subduction component in the depleted mantle source, and suggest that these rocks were formed in a supra-subduction zone tectonic setting.
Źródło:
Acta Physica Polonica A; 2016, 130, 1; 17-22
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Absorption Studies on Some Silicate and Cabal Glasses Containing NiO or $Fe_{2}O_{3}$ or Mixed NiOi + $Fe_{2}O_{3}$
Autorzy:
Moustaffa, F.
El-Batal, F.
Fayadd, A.
El-Kashef, I.
Powiązania:
https://bibliotekanauki.pl/articles/1538677.pdf
Data publikacji:
2010-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Ce
42.72.Bj
71.20.Be
76.80.+y
Opis:
Ultraviolet and visible absorption of some sodium and potassium silicate and cabal glasses containing nickel oxide, ferric oxide or both nickel and ferric oxides together have been investigated. In alkali silicate glasses, nickel ions reveal no ultraviolet absorption bands but they show characteristic visible absorption bands due to octahedral and tetrahedral coordinations while iron ions show weak visible absorption bands which are related to ferric ions mostly in tetrahedral state, especially at high alkali oxide content; also iron ions reveal charge transfer ultraviolet absorption bands which are assigned mostly to ferric ions with few ferrous contributions. The proportion of tetrahedral state increases with the increase in the alkali oxide content for the two transition metal oxides. In cabal glasses, nickel ions tend to exist mostly in octahedral state, while ferric ions exist mostly in octahedral and some in tetrahedral form, all the absorption obtained are attributed to their respective energy levels. The ratio of the different coordinations states are discussed in relation to the glass composition.
Źródło:
Acta Physica Polonica A; 2010, 117, 3; 471-477
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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